<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <script src="../vue.js"></script>
  </head>

  <body>
    <div id="app">
      <h1>全名:{{fullName}}</h1>
    </div>
    <script>
      Vue.config.productionTip = false;

      /* 
        使用watch来书写获取全名的逻辑,感受watch和computed的区别
      */
      const vm = new Vue({
        el: "#app",
        data() {
          return {
            firstName: "wang",
            lastName: "zhongwang",
            fullName: "",
          };
        },
        watch: {
          firstName: {
            immediate: true,
            handler() {
              this.fullName =
                this.firstName.toLowerCase() +
                " " +
                this.lastName.toLowerCase();
            },
          },
          lastName: {
            immediate: true,
            handler() {
              this.fullName =
                this.firstName.toLowerCase() +
                " " +
                this.lastName.toLowerCase();
            },
          },
        },
      });
    </script>
  </body>
</html>
